Methods for producing molded composites, employing polymeric and either metallic or non-metallic materials, useful for example for making entry way doors or furniture components, are well known in the art. Typically, such molded composites are manufactured by reactive molding processes, such as for example polyurethane reaction injection molding (RIM) in which a polyisocyanate, a polyol, and a chain extender are brought together in a single operation (the polyol and chain extender may be preblended if desired) and immediately injected into a mold cavity containing a metallic or non-metallic insert upon which the curing polyurethane forms a decorative shell. The insert or substrate reduces the amount of polyurethane precursor materials which must be injected, and additionally provides structural support for the finished molded composite. Other methods for producing molded composites include gel coat processes in which a polymeric material intended to form the exposed surface of the article is sprayed into the mold cavity. An alternative method is the sheet molding process in which a fibrous impregnated prepreg is placed in a mold cavity and shaped by heat and pressure into the desired configuration.
The processes disclosed in the prior art result in finished surfaces which are difficult to stain or paint, and which do not accurately simulate the look and feel of natural wood, leather, etc.
U.S. Pat. No. 4,676,041, issued June 30, 1981 discloses encapsulating a core wrapped in glass fiber with a liquid catalyzed resin material which impregnates the glass fibers and simultaneously forms the outer skin or shell of a door. In order to prevent fiber readout at the surface of the door, however, the walls of the mold are first coated with the same liquid catalyzed resin material. This is commonly referred to as a "gel coat" process, and insures that the surface of the molded plastic article is devoid of glass fibers.
U.S. Pat. No. 4,550,540, issued Nov. 5, 1985, discloses the use of sheet molding compound (SMC) for preparing a compression molded door.
Finally, U.S. Pat. No. 4,250,585 discloses a method for manufacturing a water ski, by polymerizing liquid reactive components adjacent a sheet of aluminum within a mold. The formed plastic hull of the ski is mechanically adhered to the aluminum deck, and contains reinforcing elements throughout.